This invention relates to the beneficiation of lithium-containing ores and, more particularly, to a process of beneficiating such ores by froth flotation to produce a high grade concentrate of lithium values.
The world's largest proven reserve of lithium ore is in the Kings Mountain district of North Carolina. This area includes substantial deposits of pegmatites containing an average of about 15 to 20% spodumene, which is basically Li.sub.2 O.Al.sub.2 O.sub.3.4SiO.sub.2. The spodumene is associated with other gangue minerals, such as felspar, quartz and muscovite, from which it must be separated to be useable in chemical and ceramic applications.
It is known to separate spodumene and other lithium values from gangue minerals with froth flotation processes in which an aqueous pulp of the ore is conditioned with an amine collector and the gangue is floated from the spodumene fraction. U.S. Pat. No. 3,710,934 (Wyman) discloses such a process. It is also known to separate spodumene with a froth flotation process in which an aqueous pulp of the spodumene-containing ore is conditioned with an anionic-type collector, such as fatty acids and their soaps, and the spodumene fraction is recovered in the froth product. U.S. Pat. No. 2,974,884 (Martin et al) discloses such a process. In either case, the ore pulps usually must be deslimed before an acceptable flotation of the gangue minerals or spodumene can be obtained. This desliming step adds to the processing costs and, more importantly, the slime fraction, which is usually disposed as waste, contains a substantial quantity of mineral values, particularly Li.sub.2 O.